The two most common principles of operation for bearings are rolling element bearings and sliding bearings. The main purpose in both cases is to permit relative motion between two members with low frictional resistance.  Rolling element bearings carry a load by placing rolling elements between an inner and outer member.  Sliding bearings carry a load by placing a thin film of lubricant between an inner and outer member.  Alternatively no lubricant is required if one or both members are made of a low friction material.

Ball bearings: Typically the most widely used type of rolling element bearing. Some common types include: deep groove, angular contact, thrust and angular contact thrust bearings. Ball bearings are constructed of an outer race, inner race, rolling elements (spheres / balls) and an optional cage (retainer). There are single or double row ball bearings. The balls contact at a relatively small point allowing them to travel at very high speeds. Deep groove ball bearings are good for radial loads but relatively poor for axial (thrust) loads. Angular contact ball bearing design allows increased performance with axial (thrust) loads. Typical applications include electric motors, conveyor rollers, light duty gear boxes, etc.

Roller bearings: Uses cylinders of slightly greater length than diameter and are the earliest known type of rolling element bearing. Common types include: cylindrical, tapered, spherical, cylindrical thrust and needle bearings. Roller bearings are typically constructed of an outer race, inner race, rolling elements and a cage. There are single, double, or more rows of rolling elements. Roller bearings can be used at moderately high speed applications. Roller bearings have high radial load capacity but low axial (thrust) capacity. An exception is the tapered bearing which has high radial and axial capacity. Typical applications include medium to heavy duty electric motors, fabricated housings, rolling mills, pillow blocks, large gear boxes, reduction units, machine tools, vehicles, etc.

Spherical plain (friction) bearings: Simple sliding type (metal on metal) bearings. Some common types include: spherical, spherical rod end, spherical angular contact and spherical thrust bearing. Spherical bearings are a simple bearing design consisting of a spherically ground inner ring housed in a mating outer ring without any rolling elements. A spherical bearing requires constant lubrication, but can be maintenance free depending on sliding surfaces and application. Typically used in low to moderate continuous speed applications.

Bushings / journal bearings: Simple sliding type (metal on metal) bearing. Some common types include bushing, flanged bushing, split bushing and thrust washer. These bearings require periodic lubrication, or can be maintenance free depending on sliding surfaces and application. Typically used in low to moderate continuous speed applications.

Solid pillow block housings: Housing that holds rolling element (ball) bearings. Pillow block housings are usually cast iron, cast steel, machined steel or rolled steel. The housing has concave sphered inner surface to accept deep groove ball bearing with convex sphered outer surface. Pillow block bearings permit moderate initial misalignment. Typical applications include: conveyor rolls, press rolls, conveyor deck shafts, etc.

Split pillow block housings: Housing that hold rolling element (self aligning ball or spherical) bearings or sliding bearings. Split pillow block housings are usually mad of cast iron, cast steel, machined steel or rolled steel.

Flanged bearing housings: Hold rolling element (ball) bearings. Flanged bearing housings are usually made of cast iron, cast steel, machined steel or rolled steel housing. The housing has concave sphered inner surface to accept deep groove ball bearing with convex sphered outer surface. Typical applications include: conveyor rolls, press rolls, conveyor deck shafts, etc.

Typical wood products industry equipment utilizing bearings are:

Logging: Feller buncher, skidder, delimber, log loader, logging trucks.

Sawmill: Debarker, canter, gang edger, board edger, resaw, lumber sorter, lumber stacker, chipper, conveyor, transfer, log deck, log feeder, step feeder, fan.

Planermill: Planer, molder, lumber sorter, lumber stacker, chipper, conveyor, transfer, fan.

Plywood Plant: Debarker, lathe, veneer clipper, dryer feeder, veneer stacker, panel stacker, chipper, conveyor, transfer, log deck, log feeder, step feeder, fan.

OSB Plant: Debarker, strander, press, panel stacker, conveyor, transfer, log deck, log feeder, step feeder, fan.

MDF Plant: Debarker, press, panel stacker, conveyor, transfer, log deck, log feeder, step feeder, fan.

Pulp and Paper Mill: Debarker, chipper, pump, paper machine, paper winder, conveyor, transfer, log deck, log feeder, step feeder, fan.

English Terminology: Bearings, bearing, bushing, bushings, ball bearings, roller bearing, flange bearings, pillow blocks, sawmill, planer mill, plywood plant, oriented strand board, medium density fibreboard, pulp, paper, wet mill, dry mill.